On many Windows systems, Microsoft's Java VM should be installed already. If it is not working,
then you can try the other suggestions below and, if all else fails, try installing the
Java Plug-In from Sun Microsystems (below).

If you have to install the Sun Java Plug-in:
The installation is available at http://java.sun.com/getjava.
You may have already completed this step and installed the Java VM from Sun.
In this case, check the steps below to help determine why it is not working.

Are Java applets enabled?

If you are using Internet Explorer 4.0, 5.0, or 5.5, then your browser's security settings may have disabled Java.
To check this:

Open Internet Options from Tools-->Internet Options (View-->Internet Options in some browsers).

Click on the Security tab at the top and then choose Custom Level.

Scroll down to the Microsoft VM section and make sure that Disable Java is not selected.

Are multiple versions of Sun's Java installed?
Some users have reported that, for them, a newly installed version of Sun's Java did not work correctly until they uninstalled all older installed versions.